The secondary capsule layer is constructed by \(N_{c}\)  capsules, where each capsule is updated by a dynamic routing process as originally proposed in [1]}. The iterative dynamic routing process first learns the coupling coefficients, \(C_{i,j}\) , between two capsules, \(i\)  and \(j\) , available in two subsequent layers. After the degree of agreement between them is computed using the routing softmax function:
\(\mathbf {C}_{i,j}=\frac{\exp ({b}_{i,j})}{\sum _{k} \exp ({b}_{i,k})},\ \) 
